ASSESSMENT OF NATURAL FLOW COMPUTATION PROCEDURES AND MONITORING NETWORK FOR ADMINISTERING APPORTIONMENT OF THE SOUTH SASKATCHEWAN RIVER BASIN AT THE ALBERTA-SASKATCHEWAN BOUNDARY Prepared by: Alberta Environmental Protection Surface Water Assessment Branch MARCH 1995 PPWB REPORT NO. 133 TABLE OF CONTENTS Page No. LIST OF FIGURES........................................................... i LIST OF TABLES............................................................ ii 1. INTRODUCTION ...................................................... 1 2. THE MASTER AGREEMENT ON APPORTIONMENT....................... 3 2.1 Pertinent Clauses................................................. 3 2.2 Interpretation of Pertinent Clauses ................................... 4 3. AUDITING OF APPORTIONMENT ....................................... 7 3.1 Projects Depletion Method ......................................... 7 3.2 Monitoring Network .............................................. 8 3.3 Problems with Procedures.......................................... 8 4. MEAN ANNUAL VOLUME, 1:10 YEAR LOW FLOW VOLUME, AND 1:20 YEAR LOW FLOW VOLUME ................................................ 15 5. WATER ALLOCATIONS .............................................. 16 6. COMPARISON OF CONSUMPTIVE ALLOCATIONS TO THE MEAN, 1:10 YEAR LOW, AND 1:20 YEAR LOW APPORTIONABLE ANNUAL FLOW VOLUME . 21 7. EVALUATION OF HYDROMETRIC MONITORING NETWORK ............. 27 7.1 Storage Projects................................................. 27 7.2 Diversion Projects ............................................... 29 7.3 Return Flows ................................................... 34 7.3.1 Assessment of Sheerness/Deadfish Return Flow Stations ........... 36 7.3.2 Assessment of Irrigation Districts Return Flow Stations ............ 37 7.4 Routing Index Stations............................................ 43 7.5 Minimum Flow Provision ......................................... 43 7.6 Need for Daily Simulation Model................................... 47 8. CONCLUSIONS...................................................... 52 9. RECOMMENDATIONS ................................................ 60 10. BIBLIOGRAPHY ..................................................... 64 APPENDICES: ............................................................. 65 Appendix A - Study Terms of Reference ................................ 66 Appendix B - South Saskatchewan River Basin Historical Monthly Natural Flows ................................................ 69 Appendix C - Evaluation of Station Contributions to Estimated District Return Flows ................................................ 73 LIST OF FIGURES Page No. FIGURE 1: MAP OF THE SOUTH SASKATCHEWAN RIVER BASIN.......... REPORT JACKET FIGURE 2: MINIMUM FLOW REQUIREMENT FOR THE SOUTH SASKATCHEWAN RIVER AT THE ALBERTA - SASKATCHEWAN BOUNDARY ............................... 5 FIGURE 3: SASKATCHEWAN AND ALBERTA'S ANNUAL SHARE OF SOUTH SASKATCHEWAN RIVER AT THE ALBERTA - SASKATCHEWAN BORDER.................................. 6 FIGURE 4: SCHEMATIC MODEL OF THE SOUTH SASKATCHEWAN RIVER AND HYDROMETRIC NETWORK CURRENTLY USED IN MONITORING APPORTIONMENT............................. 13 i LIST OF TABLES Page No. TABLE 1: PROJECTS INCLUDED IN THE COMPUTATION OF APPORTIONABLE FLOWS AND RELATED HYDROMETRIC STATIONS ................... 10 TABLE 2: SUMMARY OF LICENSED WATER USES FOR THE SOUTH SASKATCHEWAN RIVER AND ITS MAIN TRIBUTARIES ............... 16 TABLE 3 (a): LICENSED WATER USES IN THE RED DEER RIVER BASIN............. 17 TABLE 3 (b): LICENSED WATER USES IN THE BOW RIVER BASIN.................. 18 TABLE 3 (c): LICENSED WATER USES IN THE OLDMAN RIVER BASIN.............. 19 TABLE 3 (d): LICENSED WATER USES IN THE SOUTH SASKATCHEWAN RIVER BASIN ................................................................. 20 TABLE 4 (a): ASSESSMENT OF LICENSED WATER USES FOR THE RED DEER BASIN . 22 TABLE 4 (b): ASSESSMENT OF LICENSED WATER USES FOR THE BOW RIVER BASIN ................................................................. 23 TABLE 4 (c): ASSESSMENT OF LICENSED WATER USES FOR THE OLDMAN RIVER BASIN ........................................................... 24 TABLE 4 (d): ASSESSMENT OF LICENSED WATER USES FOR THE LOWER SOUTH SASKATCHEWAN RIVER BASIN.................................... 25 TABLE 4 (e): TOTAL LICENSED WATER USE..................................... 26 ii TABLE 5: MAJOR ON-STREAM STORAGE PROJECTS IN THE SOUTH SASKATCHEWAN RIVER BASIN.................................... 28 TABLE 6: ASSESSMENT OF LICENSED WATER USES FOR THE SOUTH SASKATCHEWAN RIVER .......................................... 33 TABLE 7: HYDROMETRIC STATIONS USED TO ESTIMATE RETURN FLOWS ...... 35 TABLE 8: STATION CONTRIBUTION (BASED ON REGRESSION EQUATIONS) TO DISTRICT AND TOTAL RETURN FLOWS ............................. 41 TABLE 9 (a): MONITORING SITES RECOMMENDED FOR ANNUAL WATER BALANCE OF THE SOUTH SASKATCHEWAN RIVER BASIN ..................... 48 TABLE 9 (b): ADDITIONAL MONITORING SITES REQUIRED FOR CONTINUOUS SIMULATION OF THE SOUTH SASKATCHEWAN RIVER IF TAU'S NATURAL FLOW COMPUTATIONS ARE ACCEPTED .................. 51 TABLE 9 (c): MONITORING SITES, IN ADDITION TO TABLE 9 (b), REQUIRED FOR CONTINUOUS SIMULATION OF THE SOUTH SASKATCHEWAN RIVER IF TAU'S NATURAL FLOW COMPUTATIONS ARE NOT ACCEPTED........ 51 TABLE 10 (a): MONITORING SITES RECOMMENDED FOR ANNUAL WATER BALANCE OF THE SOUTH SASKATCHEWAN RIVER BASIN ..................... 56 TABLE 10 (b): ADDITIONAL MONITORING SITES REQUIRED FOR CONTINUOUS SIMULATION OF THE SOUTH SASKATCHEWAN RIVER IF TAU'S NATURAL FLOW COMPUTATIONS ARE ACCEPTED .................. 59 TABLE 10 (c): MONITORING SITES, IN ADDITION TO TABLE 10 (b), REQUIRED FOR CONTINUOUS SIMULATION OF THE SOUTH SASKATCHEWAN RIVER IF TAU'S NATURAL FLOW COMPUTATIONS ARE NOT ACCEPTED....... 594. iii 1. INTRODUCTION The South Saskatchewan River, immediately downstream of the Alberta/Saskatchewan border, receives waters from three major sub-basin areas: the Oldman River, the Bow River, and the Red Deer River basin (Figure 1 in the jacket at the end of the report). The headwaters of the Red Deer and Bow River are entirely in the Alberta portion of the eastern face of the Rocky Mountains while the Oldman River receives flow from the Waterton, Belly, and St. Mary Rivers which have their headwaters in Montana. The sharing of waters in the South Saskatchewan River is governed by the 1909 Boundary Waters Treaty which permits the U.S.A. to divert 25% of the flow of the St. Mary River for flow rates of up to 666 cubic feet per second (cfs) and 50% of the flow in excess of 666 cfs., and by the 1969 Master Agreement On Apportionment which divided the waters of eastward flowing interprovincial streams, including the South Saskatchewan River, equitably between Alberta and Saskatchewan. Administration of the Master Agreement is carried out by the Prairie Provinces Water Board (PPWB) through the use of a number of administrative procedures, rules, and guidelines which were developed to improve the Board's ability to apportion eastward flowing interprovincial waters, and to ensure that apportionment is carried out in an equitable fashion. One of these procedures is the "South Saskatchewan River Below Red Deer River Natural Flow Calculation Procedures" which use data from 55 hydrometric stations to compute the apportionable flow (natural flow minus U.S.A. diversions) for the South Saskatchewan River at the Alberta-Saskatchewan boundary. In view of the large number of hydrometric stations required in the administrative procedure for this watercourse, the PPWB requested the Committee on Hydrology (COH) to review the administrative procedures and to evaluate the apportionment monitoring network required to administer the South Saskatchewan River basin. The purpose of the review is "... to determine the appropriate level of the hydrometric network required for apportionment monitoring". This report provides the results of the evaluation using the terms of reference established by the COH (listed in Appendix A) as a guideline. The evaluation begins by examining the 1969 Master 2 Agreement On Apportionment as it relates to the South Saskatchewan River. It then examines the natural flow computation procedures, which form the basis for apportionment, as well as the level of licensing in the basin. Lastly, the current hydrometric monitoring network is examined and recommendations are made on the location and number of hydrometric stations required in the basin to administer the Agreement. 3 2. THE MASTER AGREEMENT ON APPORTIONMENT 2.1 Pertinent Clauses The 1969 Master Agreement on Apportionment divided the waters of eastward flowing interprovincial watercourses equitably between Alberta and Saskatchewan. The general principle of the Agreement, outlined in Article 3, Schedule A, is that; "Alberta shall permit a quantity of water equal to one-half of the natural flow [less U.S.A. consumptions] of each watercourse to flow into the Province of Saskatchewan...". In the case of the South Saskatchewan River, the Agreement listed a number of additional conditions. These are: 1. Article 2C which states; "...the point at which the natural flow of the watercourses known as the South Saskatchewan and Red Deer Rivers is to be determined may be, at the option of Alberta, at a point at or as near as reasonably may be below the confluence of the said two rivers." 2. Article 4A which states; "Alberta shall be entitled in each year to consume, or to divert or store for its consumptive use a minimum of 2,100,000